These proteins include immune-modulating proteins, cell-surface antigens, proteases, angiogenic and molecules 
July 21, 2021
These proteins include immune-modulating proteins, cell-surface antigens, proteases, angiogenic and molecules . Lipids EVs are rich in lipids such as cholesterol, phosphatidylserine, diglyceride, phospholipid, phosphatidylcholine, phosphatidylinositol, polyglycerol, and phosphatidylethanolamine. DNA fragments, and lipids. Studies have demonstrated that extracellular vesicles promote angiogenesis in cellular experiments and animal models. Herein, recent reports on the use of extracellular vesicles for therapeutic angiogenesis during ischemic diseases are presented and discussed. We believe that extracellular vesicles-based therapeutics will be an ideal treatment method for patients with ischemic diseases. multi-vesicular endosomes, intraluminal vesicles, phosphatidylserine Biological characteristics of EVs EVs have three distinct types including exosomes, microvesicles (MVs), and apoptotic bodies (ApoBDs) , as classified by their biogenesis and origin. Here, we mainly summarize the generation, composition, and isolation of EVs. Generation of EVs (Fig.?1) Open in a separate window Fig. 1 Generation and release of extracellular vesicles (EVs). a Healthy cells produce exosomes and MVs. Exosomes occur through three steps: cytomembrane recess inward to form early endosomes, intraluminal vesicle forming in multi-vesicular endosomes (MVEs) by intraluminal budding, and MVE fusing with cell membranes to release ILVs as exosomes. MVs bud outward directly from the plasma membrane. b Apoptotic cells produce ApoBDs. ApoBDs bud outward directly from the apoptotic membrane. ApoBDs are thought to Sema6d be connected with self-cleaning of aging cells and intercellular immune regulation Exosomes, defined as 50C150-nm-sized vesicles, were found and named in 1987 . The process of exosome generation can be summarized into three parts. First, the cytomembrane recesses inward to form early endosomes. Second, these early endosomes further develop into multi-vesicular endosomes (MVEs) in which intraluminal vesicles (ILVs) are formed by intraluminal budding. Finally, MVEs fuse with cell membranes to release ILVs as exosomes into the extracellular space, where they can be taken up by donor cells . Released exosomes can travel to distant tissues to affect the behavior and biological function of target cells , which bind to the surface of exosomes through CBL-0137 specific ligands. There are two CBL-0137 ways in which exosomes enter target cells , namely cellular endocytosis and membrane fusion, whereby they release their cargoes. Unlike exosomes, MVs are in the range of 100C1000?nm in CBL-0137 diameter  and are usually larger than exosomes. MVs bud from plasma membrane directly and then are released extracellularly under the condition of various stresses including irradiation, injury, and hypoxia . Many studies have shown that exosomes and MVs are generated from healthy cells, while ApoBDs are mainly produced by dying cells or apoptotic cells . The role of ApoBDs in intercellular communication is currently unclear. Researchers consider the primary functions of ApoBDs are self-cleaning of aging cells and intercellular immune regulation [20C22]. Composition of EVs Proteins Proteins in EVs are mainly derived from plasma membrane, cytosol, Golgi, and nucleus [23, 24]. As more EV proteins are identified, it has been apparent that EVs contain a common set of EV proteins and cell-type-specific components. The common proteins include cytoskeletal proteins, heat-shock proteins, metabolic enzymes, annexins, ribosomal proteins, tetraspanins, vesicle trafficking-related proteins, and major histocompatibility complex (MHC). The purity of EV preparation is often demonstrated by protein markers enriched in EVs. In fact, tetraspanins including CD9, CD63, CD81, and CD82; heat-shock proteins (e.g., HSP70 and HSP90); MHC classes (I and II); Tsg101; 14-3-3 proteins; and the endosomal sorting complex required for transport (ESCRT-3) binding protein Alix have been regarded as specific exosomes markers for years. However, these proteins can also be detectable in ApoBDs and MVs [24, 25]. In addition, the types of cell-type-specific proteins CBL-0137 are dependent on their parental cells and conditions under which the EVs are secreted. These proteins include immune-modulating proteins, cell-surface antigens, proteases, angiogenic and molecules . Lipids EVs are rich in lipids such as cholesterol, phosphatidylserine, diglyceride, phospholipid, phosphatidylcholine, phosphatidylinositol, polyglycerol, and phosphatidylethanolamine. Specifically, exosome plasma membranes CBL-0137 contain a lot of cholesterol, sphingomyelin, ceramide, lipid rafts, and phosphatidylserine. MV and ApoBD membranes have high concentration of phosphatidylserine . The stability of EV membrane is attributed in part to the lipid content of their membranes . As a result of their high lipid content, EVs have the capacity to pass through biological barriers, escape phagocytosis by the reticuloendothelial system,.